Follyworks

you've got 4 fuses in an old xs400 - one for the Main, and then fuses for Ignition, for Signals, and for the Headlight. So if you have a dead fuse, and anything at all works, it's not the Main. If it starts and has working signals, the fuses for the ignition and signals are fine. So that mangled and missing fuse in the fuse block is likely the reason why the headlight doesn't come on. Replacing fuse holders is easy enough - I replaced my entire fuse box with new blade style fuses after I had some of the fuse holders snap as I was changing fuses.

Sometimes the forum is a little slow to respond. I've got a '78 xs400, been tweaking it out for a bit now. Biggest problem mine seems to have is with the ignition system. The old points systems keeps slipping out of adjustment, and when it does, it's a bear to start - that and making sure your carbs are clean are your most likely culprits on the hard start. A common problem on the old xs400 is a revving problem - once it's warmed up, the idle speed will climb to around 3500 rpm. If you get happenning on your bike, hunt around here, how to fix it's been covered a few times.

I replaced the coils on my '78 xs400 with ones from MikesXS, a site which heavily caters to XS650's, but many of the parts swap to other XS models. So at $24.00 for each of the 2 coils, my '78 xs400 is running great, and the 78 xs400 and a 77 xs360 have the same OEM reference number for their coils.

sounds like it's already giving you feedback as to what it needs - it needs that right cylinder firing! If it's firing intermittantly, and when you tested you got no spark on that side, it's likely an electrical issue with the ignition system giving you an issue now. Check the coils and the points - a '78 is old enough it's still using points instead of electronic ignition, and they can be a bit fiddly at best.

the peak in the background there is Hawksbill Mountain, and is about 4000 ft in elevation. Looking a differnt direction from the same overlook, I could see the valley below, at something like 1200 ft in elevation. The ground drops off fast in some of those places.

Having finally gotten my bike all tuned and running well, I decided it needed to be put to the test - 4 days of riding in and around Shenandoah National Park in the Appalachian mountains. The main road through the park is over a hundred mile long, windy and hilly, surrounded by trees, wildlife, and occasional breathtaking views, snaking along high ridges the whole length of the park. I have to say that the bike handled it all pretty well - these were roads where light and maneuverable are an asset, though camping gear strapped to her made it a bit more unwieldy then usual. Fortunately, I packed light. Averaged just shy of 60 mpg, and had no real mechanical issues. Out for some day hikes, and stopping to enjoy the view. The saddlebags are modified military surplus bags, on a custom built bag mount (having welding tools and the skills to use them comes in handy sometimes!) Loaded for travel. sleeping bag made for a decent backrest, and my tent-ish gear is tiny, so the load is minimal. I came back with tons of photos, though few of them include the bike, a sunburn on the back of my neck, from between the bottom of the helmet and top of my jacket collar, and a fresh appreciation for the plan of always bringing rain gear, no matter what the weather forecast says.

I just reiwred most of the fusebox on my '78 xs400e. In mine - RED (from battery) - to MAIN RED (going up the headlight) - from MAIN The 3 browns - all are power going in to one of the other 3 fuses. All have power when the bike is turned on with the key, and I think you could swap them around (i.e. it doesn't matter which they go to). I think, if I remember correctly, that the Red/Yellow goes to the ignition fuse, and one of the red/white wires goes to the headlight fuse, and the other red/white to the signals - however, they all use 10 amp fuses, at least in my bike, so if you've got some switched you can test easily by seeing what works. Put simply - pair one of the brown wires with one of the striped red wires. No browns go to browns, and no striped go to striped.

Well to start, if you've switched it from the original air filters to Pods, you will need to likely change out the jets. The Pods give more air flow, so the fuel mixture need adjusted accordingly. But as a seperate suggestion, start your own thread here on the forums - you're more likely to get answers for your bike instead of things about the OP's bike, and get urged to tell us all about your "new to you" bike.

what part of the wire "Came apart"? Did it come loose from the coil, break somewhere in the middle, or come free of the spark plug cap? If it's from the coil or a break in the middle, it's as Jim said (though my '78 xs400 didn't have the wasted spark coils but still had the wire moulded in). If it's just loose from the spark plug cap, that's a pretty easy fix, and can be found at most suppliers of parts.

On mine, I took the seat off, and carefully peeled the old seat cover off, duct tape and all. Then I sliced it apart to make a pattern to make a new cover out of fresh vinyl from the upholstery fabric store. Only 2 seams to sew and it went back on easily. Of course, this method requires ability to sew, or least finding someone else who can. Though if I were buying a new one, I'd probably look at JP Whitney.

While I can't say whether it will or won't work (I've looked at the system myself, I can comment on some of Jim's points. The PAMCO electronic ignition isn't a full and complete system like the factory installed systems they add later - it's a system that replaces the points. Just the points are replaced, so the bike's existing ARU unit stays put. In theory, the the advance unit in your bike, and it's mechanical effect on the ignition curve, stays the same. But with the switched side, you get position problems, as well as maybe having the shaft spinning the wrong way. So may or may not work. The electronic unit replaces the plate that the points are mounted on - so Jim's comments about mounting positions is likely dead-on. If the slots and screws aren't in the right places, there's no way you can mount it right, especially since you'd need adjustment room it to get the timing right. All that said, it seems like a useful mod to replace finicky old points systems - let us know what you work out! For those unfamilair with this particular unit, here's a link - Pamco electronic ignition - to the maker's site.

Old bulbs and an impact from dropping it could do it. But if you dropped the bike on it's left side and lost the left turn signals, I'd guess some wire got pinched, pulled, or otherwise mangled. Might not be damaged at the fixture itself, but possibly where the fixture mounts to the bike. As far as I know, the front and rear are wired such that if one bulb goes out, front or back, the other should still work. But you've got a loose wire somewhere in the connections, that might not be the case.

I'd replaced the coils on my '78 xs400 just a few months ago - used ones from Mikes XS650 site, the Part #17-6805, about halfway down the page, and seemed like a good fit - similar stats to original, fit the original mounts, and the bike runs great with them in. If you think it might just be in a wire and want to keep the coils but replace the leads to the plugs, you might have a problem - the original coils have the lead wire as part of the unit, epoxied in place (replacements, the wire is seperate), and the only way to replace it is to cut it and splice a new one on. There's a lot of voltage there, so you'd need to track down some kind of fitting to do that splice properly.

It's an old enough bike to have a points ignition system - so check things like the points gap, dwell angle, and the timing. The points ignition is very high on the list of "Reasons why this old bike doesn't start well", but at least is easier to fix then taking the carbs apart again.

And there is a thin gasket between the cover and the body, to keep moisture out. If the cover hasn't been taken off in a while, that could be holding it on like glue - a light whack ought to free it up if that's the case.

From what I know, the standard model 650 from '76 to '79 used a cap that should be the same as on a 400 (or at least was on mine). But the 'Special' model 650 from 78-84 used a different size. (8 mm bigger i guess, by XSwheels measurement). So just knowing it's a cap from a '78 xs650 isn't enough to know if it'll fit. Standard 650 or special 650? They look the same in pictures, so if it's not stated in the ad, you may need to contact the seller and ask.

I too have a 78 xs400, and it also has the stock sprockets on it. Stock everything, in fact, with the sole exception of pod air filters. And with my 200 lbs on it, it hits redline somewhere just past 90. Hate to say it, but if you're only squeezing a top speed of 60 out of it, you've got some other problem then just sprocket choice.

You can at least troubleshoot that gas gets from the tank to the carbs easily. The carb bowls have a drain on the bottom - if you undo that, you should get about a tablespoon of fuel to flow out. If you don't, then fuels not getting to the carbs. While you're at that, catch that fuel in something, and take a look at it - if it's got crud in it, you've got stuff in your tank, lines, or carbs that could clog things up.

Actually the shavings from those things are fairly easy to manage. I'd used one an old lawn mower I had, and the shavings from the tapper (no drill needed, it's all done by the hand driven tapping tool) were good sized thin spiral cuts of metal coming out on the outside end of the hole. Easily grabbed as you work, and if you miss one and it tumbles in, it's a big enough piece to spot and fish out (though awkward to fish out through the spark plug hole. So it's possible to do without removing the head, but you need to be slow and careful as you do it.

So I was adjusting the points on my xs400, and discovered to my dismay that one of the screws (the one for adjusting the right point, if it matters to anyone) seems to be at least partially stripped - still some resistance as I turn it, but it just keeps turning and turning without quite cinching down. As it's the first time I've been at these screws on this bike, I'm cursing the PO a bit, and looking at my options - do I replace the whole piece that the points assembly screws into, or see if I can come up with some way to restore the threads. I'm leery of drilling out the hole and just tapping it to the next size bigger screw, it's all a little too close to the things that I don't want metal shavings getting into. Thoughts? Suggestions?

I can see I gave too much info, and buried my actual question - though those are some of the steps I'm working though on the starting problems, Jim. Ignition coil, supposed to test at 4 ohms resistance primary circuit, 9k ohms secondary circuit. Mine test at 4 ohms primary circuit, 4.4M ohms on the secondary on the right side coil, and 3.8 ohms primary and 17k ohms on the secondary for the left side coil. Obviously, the coils are not performing at or near spec - what problems can I attribute to this, should these be replaced, and can anyone tell my a good and affordable source for them if I should be replacing them?

Ever since I got this bike (a 78 xs400e), it's been reluctant to start - nursing either the electric start or the kickstart, it would only grudgingly start up - once running, it seemed to run well, just not wanting to start up. So I went through all the obvious stuff - yes, it had spark, yep, charged battery. Hey, even good compression! Clean carbs, and once it starts, it seemed the air/fuel mix was decent. But especially with the colder weather, starting the little beast was becoming impossible. Went through the whole checklist again today, and decided that, while it was giving a visible spark, was it a "fat" spark? So decided to run through the ignition system. Battery? Fully charged and actually read as 13.1 volts Plugs? Good condition, properly gapped, but only giving a thin blue spark when I try the ignition. Points? Look real good, and gaps seem right. So pulled the gas tank off to test the coils. Check the Haynes manual, free up the appropriate wires, and stick the meter on it. Right Coil, primary circuit - 4.0 ohms. Dead on factory spec, and I'm thinking I've pulled the gas tank for nothing. But then test the secondary circuit, and got 4.38M ohms. That's a capital M, telling me that instead of the 9,000 ohms I was expecting, it says 4,380,000 ohms. Obviously, a bit off from spec. The other coil, not nearly as bad, but still off by a ways (3.8 ohms primary, 17.6k ohms secondary). This seems like my most likely culprit on weak starting now (though, once started, it's been running fine, which seems odd if the coils are that far off spec). I can find OEM coils for about $100, which seems excessive given what I paid for the bike, or ones on Mike's XS650 that say they're the same primary ohms, but look like a completely different shape and mounting methods. Anyone able to tell me whether those will work on my xs400, or give me a different source for affordable ones that match my originals?

Are you sure that it's Cruise Control, and not just that it revs high? The xs400's, from all I've read, are notorious for having a problem with revving high ( I know mine does ). The factory set idle mixture tends to be way too lean, and once warmed up the revs climb up to around 4k or so and doesn't drop back down. I'm still tweaking out mine, so I'm no expert on it - but here's a thread from a few months back on the same problem, with suggestions for the fixing process -old thread Hope this helps.

So I've got this little '78 xs400 I got a few months ago, which I got for cheap. A new battery got it running again, and it's been some cleaning and refurbishing since then. Still has the "rev's hanging" thing that's common with this model (waiting until I've done a good carb clean to tweak that out), but otherwise seems to be mechanically running great. (70 mph at 6k rpm in 6th gear, and around 55 mpg, so I'm happy with that). The gas tank has a new rattlecan paint job (and of course, I manage to scratch it less then a week after putting it back on), and the seat is recovered as the original was in shreds. Sadly, all the chrome is pitted, and rust spots appear all over the place - small, thankfully, but still there. It's at a point wher eit looks pretty good from 30 feet, but iffy from close up. Any restoration tips from the group?